Three signal smoothing filters were previously applied to the spectra, later to be made automatic baseline correction. They are: Savitzky-Golay Filter (SGF), Low Pass Filter (LPF) and Median Filter. The SGF smoothes the data, increasing the signal to noise ratio without significantly distort the signal.This is possible from a convolution of successive subsets of adjacent data points with a polynomial using the method of linear least squares [1]}. The LPF has been improved by the group through a Voight profile [2]}, which attenuates noises greater than those related to a cutoff frequency. In this way some parameters are adjusted, which are constituents of the convolution function. Finally, there is the Median, that replaces each input element (noise) by the median of the inputs of the neighbors, where the standard of neighbors is called window and moves by the full spectrum [3]}.
